Sensitivity of Shiga toxin-producing Escherichia coli (STEC) strains for colicins under different experimental conditions

Twenty Escherichia coli strains producing well-characterised colicins were tested for their inhibitory activity against five Shiga toxin-producing E. coli (STEC) strains Using different media under aerobic and anaerobic condi tions. The five STEC strains used were of serotype O26, O111, O128, O145 an d O157:H7 which are frequently isolated serotypes associated with disease i n humans. The main route of infection for humans is through the eating of b adly cooked or handled beef. The major reservoir for STEC strains in cattle is the rumen. To mimic the situation in the rumen of cattle, overlay assay s were also performed under anaerobic conditions in the presence of 30% rum en fluid. Colicins E1, E4, E8-J, K and S4 are most active against STEC stra ins under anaerobic conditions in the absence or presence of rumen fluid. T hese colicins will be used in future experiments with the aim to eradicate the presence of STEC in cattle. (C) 2001 Federation of European Microbiolog ical Societies. Published by Elsevier Science BN. All rights reserved.